Engine serial number location

[Fastinthepast]

Hello, I need the engine serial number to get my boat registered. I bought the boat out of Oklahoma and trying to register in Texas, not sure on an inboard why they even need it. Any tips on where /how to find it appreciated.
1989 bayliner Capri 5.8 liter

 

[alldodge]

Places I'm finding are the valve cove, top of the transom plate and port rear side of the engine
http://www.marine engine.com/boat-forum/showthread.php?192010-OMC-model-and-serial-no-location (I put spaces in link)